Exploring physiological answers to the body’s unusual questions

Published on Saturday, June 1, 2019

By: Kate Royals

Have you ever wondered why our bodies do certain things? Although they may be commonplace, sometimes the physiological reasons behind them are not obvious. 

University of Mississippi Medical Center faculty answer several questions that may have had you asking, “Why in the world does this happen?"

Why are people colorblind? 

Colorblindness can be inherited or acquired, according to Dr. Kimberly Crowder, UMMC chair of the ophthalmology.

“It is commonly inherited in males (about eight percent of males and less than one percent of females are colorblind),” Crowder said. “It is a maternal inheritance (the male gets the defective gene from his mom). So when you accuse your husband of not being able to match clothes’ colors, it’s actually your mother-in-law’s fault!

“There are also a number of eye diseases that can be acquired later in life that can affect a patient’s ability to see colors.”


Why do people’s mouths water before they eat anything, especially when looking at food they like?

Dr. Jim Sones, professor of medicine in the Division of Digestive Diseases and medical director of adult physician relations, said, “Saliva is produced in preparation for food to help swallow and reduce acid symptoms in the chest as you begin to eat.”

According to Dr. Jimmy Wolfe, assistant professor of neurology, the salivary glands “are innervated with sympathetic and parasympathetic fibers. You get a reflex response to prepare your mouth for eating.

“The more you like a food, the better prepared you will be, similar to how your eyes dilate more and more quickly when looking at someone you find attractive.”


Why does urine smell strange after eating asparagus?

Chemicals develop a smell when they vaporize, according to Dr. Mehul Dixit, professor of pediatric nephrology and medical director of pediatric dialysis and transplantation.

“A classic example is chlorine in water,” Dixit said. “Asparagus contains asparagusic acid, a chemical that is not volatile, so it doesn’t have the ‘rotten smell.’ Once we eat asparagus, we convert asparagusic acid into sulfur-containing chemicals that can vaporize. These ‘vapors’ stink when we pee – from urine into the air and then to our nose.

“Our body can convert asparagusic acid into these volatile, sulfur-bearing compounds within 15-30 minutes. Please eat asparagus because it’s healthy, but don’t pee for a while or the aroma will linger for others long after you exit the restaurant bathroom.”


Why is the left lung smaller than the right one?

Dr. Michael Senitko, assistant professor of pulmonology, said the lung is one of the largest organs in the body.

“We have two lungs, the left lung and the right lung,” Senitko said. “On an average there is 50 grams’ difference in their weight, with the right lung (150-720 grams) being slightly bigger. Both lungs share their space in the chest with the other organs, such as the heart, esophagus and great vessels.

“The left lung has to share more space with these organs than the right lung and is therefore a notch smaller. Other interesting facts about your lungs are that the inner surface area of both lungs is roughly the same size as a tennis court and the total length of the airways running through them is approximately 1,500 miles.”


Why do pregnant women get heartburn?

Dr. Michelle Owens, professor of obstetrics and gynecology said an old wives’ tale “is that if you have a lot of heartburn in pregnancy, your baby will have a lot of hair. While this may be true in some cases, hormones in pregnancy are actually the main contributor to pregnant-related reflux (heartburn).

“Progesterone, one of the primary hormones of pregnancy, has the effect of causing muscle relaxation. This can slow down the digestive process and contribute to constipation and delayed stomach emptying. Furthermore, the muscular ring that keeps reflux from occurring can also be relaxed by this hormone. Add that to competing for space as pregnancy grows, and it is understandable how reflux is a common occurrence in pregnancy.”

Why do some people think cilantro tastes like soap?

Dr. Scott Stringer, chair of otolaryngology and communicative sciences, said those who think cilantro tastes like soap “have a variation in a group of olfactory-receptor genes that allows them to smell the aldehydes in cilantro leaves. Aldehyde chemicals are present in both soap and cilantro. Taste is in large part dictated by smell.” 

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